These are missing parts from the commit
111ad96134.
NDK 26.1.10909125 is used by default
Minimum API level on Android is now API 21 instead of API 19. This allows the use of OpenGL ES 3.1
* Allow using specific NDK version, for CI don't use latest but required
* Default to highest available NDK version within same major release sequence
* Refactor NDK version selection